A leaked checkpoint for Anthropic's unreleased "Mythos-class" model, codenamed Numbat, has surfaced online. The checkpoint, which is approximately 7.72 TB and contains 142 tensors, is described as a mid-pretraining artifact from a large-scale training run. While it includes a reference implementation for loading and running the model, it is raw pretraining output without any post-training or RLHF, making it unsuitable for direct inference. AI
IMPACT Leaked model checkpoints can offer insights into frontier model architectures and training techniques, potentially accelerating research.
RANK_REASON This is a leaked checkpoint of an unreleased model, not an official release from the lab.
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- Anthropic
- AutoModelForCausalLM
- Claude Code
- Mythos
- numbat
- NumbatForCausalLM
- NVFP4
- safetensors
- Trainium2
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